Alarm and security systems are now common additions to many homes and businesses. Sophisticated systems are able to communicate with a control center to alert the police, fire department, security center or a property owner. Although such systems are able to communicate an intrusion or event to some extent, the user or operator of the system is unable to visually verify what actually happened at the remote location. As such, when a false alarm occurs, the user of the system or the authority in charge must physically travel to the alarm site to verify what actually happened.
Other systems based on remote video surveillance are able to monitor remote premises, but the user of the system must, from time to time, activate a remote console to view what is happening at a remote location. For example, the user of the system may have to establish a dial-up connection across normal telephone lines. A dial-up connection may represent an additional expense, since in order to monitor the remote location, the user has to remain on line for several minutes until a video image arrives. Also, since such systems are for remote monitoring only and do not provide automated video recording, any events that they happen while waiting may be lost.
Other systems employ video cameras connected to a VCR or a VCR with a time-lapse recorder. These systems are able to record large amounts of video imagery, but the information is sequential, and retrieving the information once recorded is a tedious process since the tape must be rewound and a fast search performed to avoid missing an event. Several minutes of searching are required through all the recorded information, and once the tape reaches the end, the system stops and will not record further. Another problem with systems of this kind is that they do not provide any communications in support of remote monitoring.
More recently, more intelligent video security systems have been described which employ motion detection in hardware as well in software. Some of these systems employ local storage and communications software to connect to a centralized server. Some are able to communicate an alarm event to a monitoring center, but this is carried out across dial-up lines, and there is an expense involved in the time spent while the line is in use.
U.S. Pat. No. 5,396,284 to Freeman discloses a multiple camera system, which incorporates motion detection performed by a Central Processing Unit (CPU). Once motion is detected, the CPU sends a signal to a TDM (time-division-multiplexed) controller located at a short distance. The TDM controller switches to the camera that detected the motion, and displays the video information on a monitor and, at the same time, video information is recorded on a recording media. Since the video signal has not been digitized on the side of the TDM controller, it is clear that the recording media must be a VCR. There are no provisions for storing video information on a hard disk based system and also the video information is non-digital.
U.S. Pat. No. 5,625,410 to Washino discloses a PC based system for monitoring and storing representative images from video cameras that may be utilized for security applications or monitoring applications. This system employs a video capture card, which digitizes and compresses video information from analog or digital cameras. The system displays the video information and continuously records the compressed video information on different media such as tape, hard disk or PCMCIA, or removable hard disk. Alarm-type motion sensors are used to reconfigure the system, such as altering image size and frame rates. The system may also employ a remote server, which allows a user to monitor or continuously record video information. The preferred embodiment does not disclose a particular motion detection algorithm, however.
U.S. Pat. No. 4,511,886 to Rodriguez discloses an electronic security and surveillance system having a central monitoring station which can be located over large distance, for example across microwave links. In order to transmit the video signal over distance the video information is modulated onto a carrier.
U.S. Pat. No. 5,581,297 to Koz discloses a low-power video security system which detects motion from a single video camera, a digital compression subsystem compresses the image, and starts transmitting the compressed image over ISDN lines to a monitoring facility. Koz does not disclose a system with a plurality of cameras, nor will the system work on a network or Internet.